Internal combustion engines that utilize spark ignition combustion processes commonly include an ignition coil that is dedicated to a single spark plug. The ignition coil is used to develop a spark-initiating current that is sent to the spark plug, thereby allowing the spark plug to generate a spark which initiates combustion of a fuel and air mixture within a combustion chamber of the internal combustion engine. In one arrangement, as exemplified in United States Patent Application Publication US 2012/0299679 A1 to Kobayashi et al., the ignition coil is arranged to be mounted over an opening which receives the spark plug. The ignition coil of Kobayashi et al. includes a core around which is wound a primary winding. A secondary winding is wound around the primary winding such that a high voltage is induced on the secondary winding when an electric current applied to the primary winding is stopped. A high voltage end of the secondary winding is connected to a high voltage terminal which is in electrical communication with the spark plug, thereby delivering the spark-generating current to the spark plug. In order to facilitate mounting the ignition coil over the opening which receives the spark plug, the high voltage terminal is placed near the middle along the axial length of the secondary winding. Accordingly, the high voltage end of the secondary winding must be routed axially back along the length of the secondary winding as well as radially outward from the secondary winding to reach the high voltage terminal. This routing of the high voltage end of the secondary winding increases the height of the ignition coil, thereby increasing the packaging space needed for the ignition coil. Additionally, the high voltage end of the secondary coil is susceptible to electric field concentrations because it is the furthest point at the end of the secondary winding and is surrounded by surfaces, for example the case of the ignition coil, that are at or near ground potential. Electric field concentrations may be magnified by sharp points, for example, sharp points of solder known as solder icicles formed in the soldering process used to join the end of the secondary winding to the high voltage terminal. These localized occurrences of high electric field concentrations may lead to failure of insulating material, and consequently failure of the ignition coil.
What is needed is an ignition coil which minimizes or eliminates one or more of the shortcomings as set forth above.